题目内容
化简：cos
+cos
+cos
+cos
=______．
| π |
| 5 |
| 2π |
| 5 |
| 3π |
| 5 |
| 4π |
| 5 |
cos
+cos
+cos
+cos
=cos
+cos
+cos(π-
)+cos(π-
)
=cos
+cos
-cos
-cos
=0．
故答案为0．
| π |
| 5 |
| 2π |
| 5 |
| 3π |
| 5 |
| 4π |
| 5 |
=cos
| π |
| 5 |
| 2π |
| 5 |
| 2π |
| 5 |
| π |
| 5 |
=cos
| π |
| 5 |
| 2π |
| 5 |
| 2π |
| 5 |
| π |
| 5 |
故答案为0．
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